Role of oncogenes in chemical carcinogenesis: extrapolation from rodents to humans

Abstract

Proto-oncogenes are cellular genes that are expressed during normal growth and development processes. These genes can be activated to cancer-causing oncogenes by point mutations or by gross DNA rearrangement, such as chromosomal translocation or gene amplification. Activated versions of proto-oncogenes have been observed in various human and rodent tumours. Examples will be discussed, as will the activation of proto-oncogenes by chemical carcinogens. Most chemicals are classified as potentially hazardous to humans on the basis of long-term carcinogenesis studies in rodents. Oncogene analysis of tumours of spontaneous origin and from carcinogenesis studies may aid in risk analyses on the basis of rodent carcinogenesis studies.